[1.6.x] Added release date to 1.5 release notes.
[1.6.x] Added release date to 1.5 release notes.

Forwardport of 61283a8208 from 1.5.x

redhat-openstack/django,redhat-openstack/django,django-nonrel/django,django-nonrel/django,dex4er/django,redhat-openstack/django,django-nonrel/django,felixjimenez/django,django-nonrel/django,redhat-openstack/django,dex4er/django,felixjimenez/django,felixjimenez/django,felixjimenez/django,dex4er/django